Landfill leachate secreted from the compressed wastes in landfills over time is toxic to natural ecosystem and poses serious health issues for communities and surrounding environment. The dual role of microalgae for leachate remediation and biomass production make them one of the most sustainable renewable systems for leachate quality improvement Ultra-membrane treated leachate from Istanbul municipal landfill was evaluated in three laboratory scale experimental sets for the growth of indigenous microalgal strains and ammonium nitrogen (NH4+-N) removal. Among all the dilutions of leachate 50% showed better microalgal growth curves, but significantly lesser than control nutrient media. NH4+-N removal was systematically decreasing with increasing leachate concentration. Highest removal efficiency (100%) was observed in 10% TL (similar to 50 mg/L NH4+-N). Overall quality of TL was improved in terms of NH4+-N removal which is considered as one of the most persistant pollutants pertaining to leachate toxicity. The issues discussed in the paper can be a focus point to further improve leachate quality. (C) 2017 Elsevier Ltd. All rights reserved.